package thinkingInJava.io;

//: net/mindview/util/Directory.java
//Produce a sequence of File objects that match a
//regular expression in either a local directory,
//or by walking a directory tree.
import java.util.regex.*;
import java.io.*;
import java.util.*;

public final class Directory {
public static File[]
local(File dir, final String regex) {
 return dir.listFiles(new FilenameFilter() {
   private Pattern pattern = Pattern.compile(regex);
   public boolean accept(File dir, String name) {
     return pattern.matcher(
       new File(name).getName()).matches();
   }
 });
}
public static File[]
local(String path, final String regex) { // Overloaded
 return local(new File(path), regex);
}
// A two-tuple for returning a pair of objects:
public static class TreeInfo implements Iterable<File> {
 public List<File> files = new ArrayList<File>();
 public List<File> dirs = new ArrayList<File>();
 // The default iterable element is the file list:
 public Iterator<File> iterator() {
   return files.iterator();
 }
 void addAll(TreeInfo other) {
   files.addAll(other.files);
   dirs.addAll(other.dirs);
 }
 public String toString() {
   return "dirs: " + PPrint.pformat(dirs) +
     "\n\nfiles: " + PPrint.pformat(files);
 }
}
public static TreeInfo
walk(String start, String regex) { // Begin recursion
 return recurseDirs(new File(start), regex);
}
public static TreeInfo
walk(File start, String regex) { // Overloaded
 return recurseDirs(start, regex);
}
public static TreeInfo walk(File start) { // Everything
 return recurseDirs(start, ".*");
}
public static TreeInfo walk(String start) {
 return recurseDirs(new File(start), ".*");
}
static TreeInfo recurseDirs(File startDir, String regex){
 TreeInfo result = new TreeInfo();
 for(File item : startDir.listFiles()) {
   if(item.isDirectory()) {
     result.dirs.add(item);
     result.addAll(recurseDirs(item, regex));
   } else // Regular file
     if(item.getName().matches(regex))
       result.files.add(item);
 }
 return result;
}
// Simple validation test:
public static void main(String[] args) {
 if(args.length == 0)
   System.out.println(walk("."));
 else
   for(String arg : args)
    System.out.println(walk(arg));
}
} ///:~

